Within photonic devices, light energy is used for exciting electrons to higher energy levels and creating electrical energy or currents responsive to the light energy. The recombination of photo generated electrons and holes is a major source of energy loss within photonic devices. Examples of photonic devices include photovoltaic diodes, biological light harvesting complexes (LHCs), organic light emitting diodes (OLEDs) and organic photovoltaic cells (OPVs). Biological light harvesting complexes prevent recombination via the use of cascade structures which lead to spatial separation of charge carriers. Organic photovoltaic cells use nanoscale morphology to provide a high rate of electron hole encounters which results in the formation of spin triplet excitons. OPVs would have poor quantum efficiencies if every encounter led to recombination, but state-of-the-art OPVs demonstrate better quantum efficiency. This suppression of recombination between electrons and holes has been engineered to the interplay of spin, orbital angular momentum and delocalization of electron excitations in organic semiconductors. Time resolve spectroscopy can be used to study different engineered models having high efficiency polymer-fullerene systems in which the lowest lying molecular triplet exciton (T1) lies below the intermolecular charge transfer state (CT). Encounters of spin-uncorrelated electrons and holes generate CT states with both spin singlet (1CT) and spin triplet (3CT) characters. Triplet exciton formation can be the major loss mechanism in OPVs. The CT energy lies below T1 making relaxation from 3CT to T1 energetically favored. However, the more efficient 1:3 blend no triplet formation is possible at room temperature, but at low temperatures, bi-molecular triplet formation can be observed in this blend. This suggests that there is a thermally activated process that competes with relaxation to T1. This process is disassociation of 3CT back to free charges. However, even when energetically favored, the relaxation of 3CT spin triplet and CT back to T1 can be strongly suppressed via control over wave function delocalization, allowing for the disassociation of 3CT back to free charges (FC). This reduces recombination and enhances device performance. Thus, some manner for increasing the suppression of electron/hole recombination would further improve the efficiencies of these types of photonic devices.